In the prior art, methods for securing transmission of electronic data with the aid of digital encryption techniques are known.
US Patent Application 2002/059146 A1 shows a method for identifying a user and for secure transmission of numerical codes. In it, a transaction code is used by encryption of a random number with the user's PIN, which is known only to the user and a center. It is disadvantageous here that the fact that the PIN could be surreptitiously viewed threatens the security of this method.
Austrian Patent Disclosure AT 504 634 B1 and International Patent Disclosure WO 2008 151 209 A1, also published as US Patent Application 2008/298588 A1, disclose methods for transferring encrypted messages. In these methods, by alternatingly using symmetrical and asymmetrical keys, such as RSA key pairs, a message is sent via a third communication point, the so-called authentication device, which enables transmission of the message only once the sender and receiver and corresponding transmission of keys have been successfully identified to one another. The disadvantage of this teaching is that a third communications point, for instance in the form of a server, must be operated permanently.
International Patent Disclosure WO 2008 076 442 A1 teaches a method for randomizing the sequence of numbers on a number field, from which field a PIN is for instance input. The mechanical number field remains unchanged, but in inputting the user ignores the (standardized) digital labeling of the keys. Via a display on the screen, he is given a new distribution of the numbers 0 through 9, after which he inputs his PIN in the number field. This makes it more difficult for third parties to see the PIN surreptitiously. A disadvantage is that this security provision is ineffective if third-party spies also know the algorithm for randomizing the number sequences.
US Patent Application 2003/182558 A1 also shows a method for randomizing numbers in a number field, in which the numbers are additionally displayed on a touch-sensitive screen in a different geometry from the conventional keyboard arrangement. The disadvantage of the ineffective protection once the display algorithm is known, however, remains.